/Engine/Source/Runtime/ApplicationCore/Public/GenericPlatform/Accessibility/GenericAccessibleInterfaces.h
Returns the window at the top of this widget's hierarchy. This function may return itself for accessible windows, and could return nullptr in cases where the widget is not currently part of a hierarchy.
The root window in this widget's widget tree, or nullptr if there is no window.
[TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [IAccessibleWidget](API\Runtime\ApplicationCore\GenericPlatform\Accessibility\IAccessibleWidget) > GetWindow() const